List Agents

List all agents visible to the current identity.

TOS-419 optional filters: archetype and tag (a tag slug) narrow the result server-side. Both are AND-combined when present.

TOS-595: the system-only integration archetype is accepted HERE as a read filter (it surfaces the caller's integration-agent wrappers), even though it is rejected as a manual assignment on PUT /api/agents/{id}. The accepted read set is therefore ALL_ARCHETYPES; any other value is 422.

TOS-3512: returns the trimmed AgentSummaryResponse shape - no system_prompt/config - since those two fields alone accounted for ~95% of a measured 431KB/56-agent payload. A caller needing either field fetches GET /api/agents/{agent_id}, which still returns the full AgentResponse.

TOS-3663 follow-up: serialized through _agent_list_payloads rather than a FastAPI response_model, so the owner-only omission contract applies here too. list_agents_for returns every is_global agent plus any agent the caller holds a viewer grant on, so this endpoint hands most of its rows to a NON-owner; before this it shipped model_bundle, the since-retired reply_style and autonomy_tier, default_mode, self_improvement_mode and the owner's listing consent record to each one. Declaring the model here is what bypassed the contract, which is why response_model is now pinned to None by a test.